Organic compound and organic light-emitting device

ABSTRACT

An organic compound represented by formula [1], where in formula [1], R1 to R8 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, and other substituents, and X1 is oxygen, sulfur, selenium, tellurium, or a CR9R10 group, in which R9 and R10 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, and other substituents, and at least one of R1 to R8 is a group represented by formula [2].

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to an organic compound and an organic light-emitting device including the same.

Description of the Related Art

An organic light-emitting device (hereinafter, also referred to as an “organic electroluminescent device” or “organic EL device”) is an electronic device including a pair of electrodes and an organic compound layer disposed between these electrodes. The injection of electrons and holes from these pairs of electrodes generates excitons in the light-emitting organic compounds in the organic compound layer, and when the excitons return to the ground state, the organic light-emitting device emits light.

Organic light-emitting devices have recently made remarkable progress. They have achieved low-driving voltage, various emission wavelengths, and fast response time. The use of these devices has made it possible to make light-emitting apparatuses thinner and lighter.

Examples of high-efficiency light-emitting devices include devices containing high-efficiency materials, such as phosphorescent materials and delayed fluorescent materials.

U.S. Patent Application Publication No. 2018/0170894 (hereinafter PTL 1) describes compound A-1 below. International Publication No. 2006/114966 (hereinafter PTL 2) describes compound A-2 below.

However, when compound A-1 described in PTL 1 and compound A-2 described in PTL 2 are used for organic light-emitting devices, there is a disadvantage with luminous efficiency.

SUMMARY OF THE INVENTION

The present disclosure has been accomplished in light of the foregoing disadvantages and provides an organic compound having high luminous efficiency and also provides an organic light-emitting device superior in luminous efficiency and driving durability characteristics.

According to one aspect of the present disclosure, there is provided an organic compound represented by formula [1]:

where in formula [1], R₁ to R₈ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, X₁ is oxygen, sulfur, selenium, tellurium, or a CR₉R₁₀ group, where R₉ and R₁₀ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, in which at least one of R₁ to R₈ is a group represented by formula [2]:

where in formula [2], R₁₁ to R₁₅ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, and *1 represents a binding position, in which at least one of R₁₁ to R₁₅ is an amino group represented by any of formulae [3-1] to [3-30], and each of the amino groups represented by formulae [3-1] to [3-30] optionally further contains a substituent,

where in formulae [3-1] to [3-30], each X₂ is independently selected from the group consisting of a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, and a substituted or unsubstituted pyridyl group, and each *2 represents a binding position.

Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates electron orbital distributions of highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs).

FIG. 2 illustrates molecular aspect ratios.

FIG. 3 is a schematic cross-sectional view of an example of a display apparatus including organic light-emitting devices according to an embodiment of the present disclosure.

FIG. 4 is a schematic view of an example of a display apparatus according to an embodiment of the present disclosure.

FIG. 5A is a schematic view of an example of an image pickup apparatus according to an embodiment of the present disclosure, and FIG. 5B is a schematic view of an example of an electronic apparatus according to an embodiment of the present disclosure.

FIG. 6A is a schematic view of an example of a display apparatus according to an embodiment of the present disclosure, and FIG. 6B is a schematic view of an example of a foldable display apparatus.

FIG. 7A is a schematic view of an example of a lighting apparatus according to an embodiment of the present disclosure, and FIG. 7B is a schematic view of an example of an automobile including an automotive lighting unit according to an embodiment of the present disclosure.

FIG. 8A is a schematic view of an example of a wearable device according to an embodiment of the present disclosure, and FIG. 8B is a schematic view of another example of a wearable device according to an embodiment of the present disclosure.

FIG. 9A is a schematic view of an example of an image-forming apparatus according to an embodiment of the present disclosure, and

FIGS. 9B and 9C are each a schematic view of an example of an exposure light source of an image-forming apparatus according to an embodiment of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS Organic Compound

An organic compound according to an embodiment will be described. The organic compound according to this embodiment is represented by formula [1].

R₁ to R₈

In formula [1], R₁ to R₈ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group,

Non-limiting examples of the halogen atom include fluorine, chlorine, bromine, and iodine.

Non-limiting examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a sec-butyl group, an octyl group, a cyclohexyl group, a 1-adamantyl group, and a 2-adamantyl group. As the alkyl group, an alkyl group having 1 to 10 carbon atoms can be used.

Non-limiting examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a 2-ethyloctyloxy group, and a benzyloxy group. As the alkoxy group, an alkoxy group having 1 to 10 carbon atoms can be used.

Non-limiting examples of the amino group include an N-methylamino group, an N-ethylamino group, an N,N-dimethylamino group, an N,N-diethylamino group, an N-methyl-N-ethylamino group, an N-benzylamino group, an N-methyl-N-benzylamino group, an N,N-dibenzylamino group, an anilino group, an N,N-diphenylamino group, an N,N-dinaphthylamino group, an N,N-difluorenylamino group, an N-phenyl-N-tolylamino group, an N,N-ditolylamino group, an N-methyl-N-phenylamino group, an N,N-dianisolylamino group, ab N-mesityl-N-phenylamino group, an N,N-dimesitylamino group, an N-phenyl-N-(4-tert-butylphenyl)amino group, an N-phenyl-N-(4-trifluoromethylphenyl)amino group, an N-piperidyl group, a carbazolyl group, and an acridyl group.

Non-limiting examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an indenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a phenanthryl group, a triphenylenyl group, a pyrenyl group, an anthracenyl group, a perylenyl group, a chrysenyl group, and a fluoranthenyl group. As the aromatic hydrocarbon group, an aromatic hydrocarbon group having 6 to 60 carbon atoms can be used.

Non-limiting examples of the heterocyclic group include a pyridyl group, a pyrimidinyl group, a pyrazinyl group, a triazinyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, and a phenanthrolinyl group. As the heterocyclic group, a heterocyclic group having 3 to 60 carbon atoms can be used.

Non-limiting examples of the aryloxy group include a phenoxy group and a naphthoxy group.

Non-limiting examples of the heteroaryloxy group include a furanyloxy group and a thienyloxy group.

Non-limiting examples of the silyl group include a trimethylsilyl group and a triphenylsilyl group.

Non-limiting examples of substituents that may be further contained in the alkyl group, the alkoxy group, the amino group, the aromatic hydrocarbon group, the heterocyclic group, the aryloxy group, and the heteroaryloxy group include alkyl groups, such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, and a tert-butyl group; aralkyl groups, such as a benzyl group; aromatic hydrocarbon groups, such as a phenyl group, a biphenyl group, and a naphthyl group; heterocyclic groups, such as a pyridyl group, a pyrrolyl group, a pyrazinyl group, and a triazinyl group; amino groups, such as a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, and a ditolylamino group; alkoxy groups, such as a methoxy group, an ethoxy group, and a propoxy group; aryloxy groups, such as a phenoxy group; halogen atoms, such as fluorine, chlorine, bromine, and iodine atoms; and a cyano group.

X₁

X₁ is oxygen, sulfur, selenium, tellurium, or a CR₉R₁₀ group. X₁ can be oxygen or sulfur.

R₉ and R₁₀ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group.

Specific examples of the halogen atom, the alkyl group, the alkoxy group, the amino group, the aromatic hydrocarbon group, the heterocyclic group, the aryloxy group, the heteroaryloxy group, and the silyl group that are represented by R₉ and R₁₀ include, but are not limited to, the same as those described for R₁ to R₈. As the alkyl group, an alkyl group having 1 to 10 carbon atoms can be used. As the alkoxy group, an alkoxy group having 1 to 10 carbon atoms can be used. As the aromatic hydrocarbon group, an aromatic hydrocarbon group having 6 to 60 carbon atoms can be used. As the heterocyclic group, a heterocyclic group having 3 to 60 carbon atoms can be used. Specific examples of substituents that may further be contained in the alkyl group, the alkoxy group, the amino group, the aromatic hydrocarbon group, the heterocyclic group, the aryloxy group, and the heteroaryloxy group include, but are not limited to, the same as those described for R₁ to R₈.

In the organic compound according to the embodiment, at least one of R₁ to R₈ is a group represented by formula [2], and at least one of groups in one of the set of R₁ to R₄ and the set of R₅ to R₈ can be a group represented by formula [2].

In formula [2], R₁₁ to R₁₅ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, and *1 represents a binding position.

Specific examples of the halogen atom, the alkyl group, the alkoxy group, the amino group, the aromatic hydrocarbon group, the heterocyclic group, the aryloxy group, the heteroaryloxy group, and the silyl group that are represented by R₁₁ to R₁₅ include, but are not limited to, the same as those described for R₁ to R₈. As the alkyl group, an alkyl group having 1 to 10 carbon atoms can be used. As the alkoxy group, an alkoxy group having 1 to 10 carbon atoms can be used. As the aromatic hydrocarbon group, an aromatic hydrocarbon group having 6 to 60 carbon atoms can be used. As the heterocyclic group, a heterocyclic group having 3 to 60 carbon atoms can be used. Specific examples of substituents that may further be contained in the alkyl group, the alkoxy group, the amino group, the aromatic hydrocarbon group, the heterocyclic group, the aryloxy group, and the heteroaryloxy group include, but are not limited to, the same as those described for R₁ to R₈.

In the organic compound according to the embodiment, at least one of R₁₁ to R₁₅ is an amino group represented by any of formulae [3-1] to [3-30], and at least one of the group consisting of R₁₁, R₁₂, R₁₄, and R₁₅ can be an amino group represented by any of formulae [3-1] to [3-30]. At least one of the group consisting of R₁₁, R₁₂, R₁₄, and R₁₅ means that a group may be selected one or more among R₁₁, R₁₂, R₁₄, and R₁₅.

In formulae [3-1] to [3-30], each X₂ is independently selected from the group consisting of a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, and a substituted or unsubstituted pyridyl group. X₂ groups may be the same or different from each other. Each X₂ can be a substituted or unsubstituted alkyl group. Each *2 represents a binding position.

Specific examples of the alkyl group represented by X₂ include, but are not limited to, the same as those described for R₁ to R₈. As the alkyl group, an alkyl group having 1 to 10 carbon atoms can be used. Specific examples of substituents that may further be contained in the alkyl group, the phenyl group, the naphthyl group, and the pyridyl group include, but are not limited to, the same as those described for R₁ to R₈.

Each of the amino groups represented by formulae [3-1] to [3-30] may further contain a substituent. The substituent that may further be contained in each of the amino groups represented by formulae [3-1] to [3-30] is not limited to a particular substituent but can be selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a pyridyl group, a pyrazinyl group, a triazinyl group, a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, a ditolylamino group, a methoxy group, an ethoxy group, a propoxy group, a phenoxy group, fluorine, chlorine, bromine, iodine, and a cyano group.

A method for synthesizing an organic compound according to the embodiment of the present disclosure will be described below. The organic compound according to the embodiment of the present disclosure is synthesized, for example, by a reaction scheme described below.

Here, the compound represented by formula [1] can be synthesized by appropriately changing compounds (a) to (c). The synthesis method is not limited thereto.

The organic compound according to the embodiment has features described below. Thus, the use of the organic compound according to the embodiment for an organic light-emitting device allows the organic light-emitting device to have high luminous efficiency and superior driving durability characteristics. A basic skeleton according to the embodiment refers to a skeleton in which R₁ to R₈ of the compound represented by formula [1] are all hydrogen atoms, and in addition, when X₁ is a CR₉R₁₀ group, each of R₉ and R₁₀ is a hydrogen atom.

(1) The organic compound has a small energy gap between S₁ and T₁ because it has a ring structure containing an electron-withdrawing carbonyl group, the ring structure being a basic skeleton, and has an electron-donating amino group containing X₂ serving as a sterically hindering group.

(2) The organic compound has a low molecular aspect ratio and superior film properties because it has the basic skeleton having a high degree of flatness and the electron-donating amino group containing at least X₂ serving as a sterically hindering group.

These features will be described below.

(1) The organic compound has a small energy gap between S₁ and T₁ because it has a ring structure containing an electron-withdrawing carbonyl group, the ring structure being a basic skeleton, and because has an electron-donating amino group containing X₂ serving as a sterically hindering group.

The inventors have focused on electron distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a compound in creating the organic compound represented by formula [1].

As illustrated in FIG. 1, in each of exemplified compounds B-1, B-2, and D-21 according to the embodiment, a moiety occupying the electron orbital distribution of the HOMO and a moiety occupying the electron orbital distribution of the LUMO are separated. It can be seen that a portion occupying both the HOMO and LUMO is small. This leads to a small overlap integral and a small energy difference between the excited singlet state (S₁) and the excited triplet state (T₁). Specifically, the energy gaps between S₁ and T₁ of exemplified compounds B-1, B-2, and D-21 are as small as 0.0004 eV, 0.0035 eV, and 0.0005 eV, respectively. In contrast, the energy gaps between S₁ and T₁ of the comparative compounds 1 and 2 are as large as 0.21 eV and 0.24 eV, respectively. Comparative compound 1 is compound A-1 described in PTL 1, and the comparative compound 2 is compound A-2 described in PTL 2.

This feature is based on the effects of having a fused-ring structure, as the basic skeleton, with an electron-withdrawing carbonyl group bonded while a ring structure is formed, and also having an electron-donating amino group containing X₂ serving as a sterically hindering group. The sterically hindering group used in the present disclosure is X₂ of each of the amino groups represented by formulae [3-1] to [3-30]. This sterically hindering group has the effect of twisting the structure of each amino group that is represented by any of formulae [3-1] to [3-30] and that is bonded to the group represented by formula [2].

In the case of a compound, such as comparative compound 1 or 2, containing an amino group with no sterically hindering group, there is a large overlap between a moiety occupying the electron orbital distribution of the HOMO and a moiety occupying the electron orbital distribution of the LUMO. This results in a large energy gap between S₁ and T₁.

The above calculation results were visualized using molecular orbital calculations. As the molecular orbital calculation method, the density functional theory (DFT), which is widely used at present, was used with the B3LYP functional and 6-31 G* as the basis function.

The molecular orbital calculation method was performed using Gaussian 09 (Gaussian 09, Revision C.01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford Conn., 2010), which is widely used at present.

As described above, the compound according to the embodiment is characterized in that the energy difference between S₁ and T₁ is small. The use of the compound according to the embodiment in the light-emitting layer of an organic light-emitting device enables the device to have high luminous efficiency. The reason for this is as follows: For excitons consisting of singlet and triplet excitons in a ratio of 1:3, the triplet excitons, which undergo thermal deactivation normally, can be used for delayed fluorescence from the excited singlet state due to the small energy difference between S₁ and T₁. To convert the triplet excitons into the excited singlet state, a smaller energy difference between S₁ and T₁ is advantageous because of a smaller energy barrier. The compound according to the embodiment has a small energy difference between S₁ and T₁, easily converts the triplet excitons into the excited singlet state, and thus can provide a device having high luminous efficiency.

(2) The organic compound has a low molecular aspect ratio and superior film properties because it has the basic skeleton having a high degree of flatness and the electron-donating amino group containing at least X₂ serving as a sterically hindering group.

The inventors have focused on the flatness of the compound represented by the formula [1] in creating the organic compound. The basic skeleton of the compound according to the embodiment has a structure in which an electron-withdrawing carbonyl group is fused while a six-membered ring is formed, and thus the structure has a high degree of flatness. The high degree of flatness easily causes molecular stacking. In other words, molecular association may occur easily. In organic light-emitting devices, molecular association leads to a decrease in efficiency due to concentration quenching. The molecular association is also disadvantageous for reverse intersystem crossing. This is because triplet-triplet exciton annihilation (TTA) due to energy transfer of triplet excitons between molecules occurs easily, and reverse intersystem crossing to singlet excitons does not easily occur.

The inventors have conceived the introduction of a sterically hindering group-containing amino group represented by any of formulae [3-1] to [3-30]. The introduction of the sterically hindering group-containing amino group enables reductions in molecular aspect ratio and molecular association.

The molecular aspect ratio used in an embodiment of the present disclosure is defined as the ratio of the maximum molecular length (molecular diameter) in the xy-plane containing the basic skeleton to the molecular length (molecular thickness) in the z-axis direction perpendicular to the xy-plane containing this basic skeleton, i.e., molecular aspect ratio=(molecular diameter)/(molecular thickness). In other words, a higher molecular aspect ratio results in a higher degree of flatness. A lower molecular aspect ratio results in a lower degree of flatness and can reduce molecular association. Specifically, the molecular aspect ratio is preferably 5.0 or less, more preferably 3.0 or less.

The molecular lengths of the molecular diameters and the molecular thicknesses were calculated from the molecular lengths in ball-and-bond representations using molecular structures determined from optimized structure calculations.

FIG. 2 presents the comparison results of the molecular aspect ratios. FIG. 2 indicates that the molecular aspect ratios of exemplified compounds B-1, B-2, and B-15 are 2.7, 1.8, and 3.3, respectively, whereas the molecular aspect ratio of comparative compound 1 is as large as 7.5. This is because the compound according to the embodiment contains a sterically hindering group-containing amino group.

As described above, since the compound according to the embodiment has a low molecular aspect ratio, molecular stacking is less likely to occur, and thus molecular association is less likely to occur.

This feature is also effective in improving the amorphous nature of the organic compound. When the compound according to the embodiment is used in the organic layer of an organic light-emitting device, a stable amorphous film that is less likely to crystallize is formed, and the organic light-emitting device has high durability without the occurrence of crystallization even in the case of long-term operation.

This feature is also effective in improving sublimability. The improvement of sublimability enables the purification of the material by sublimation and the production of an organic light-emitting device by vapor deposition. This can reduce the amount of impurities contained in the organic light-emitting device and can inhibit deteriorations in luminous efficiency and driving durability due to impurities.

The organic compound can further satisfy the following conditions (3) to (6).

(3) At least one of groups in one of the set of R₁ to R₄ and the set of R₅ to R₈ is a group represented by formula [2].

This is because, when this condition is satisfied, the molecular aspect ratio is decreased. Specifically, as illustrated in FIG. 2, exemplified compounds B-1 and B-2, in which one of R₁ to R₄ is the group represented by formula [2], have a lower molecular aspect ratio than exemplified compound B-15, in which one of R₁ to R₄ and one of R₅ to R₈ are the groups represented by formula [2]. This can further reduce molecular association, as described in feature (2) above. When this condition is satisfied, groups in the other set of the set of R₁ to R₄ and the set of R₅ to R₈ can each be selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, and a cyano group.

(4) X₁ is oxygen or sulfur.

This is because when this condition is satisfied, an oxygen atom and a sulfur atom have many unpaired electron pairs, thus leading to a more stable compound against repeated redox reactions in an organic light-emitting device.

(5) At least one of R₁₁, R₁₂, R₁₄, or R₁₅ is an amino group represented by any of formulae [3-1] to [3-30].

This is because when this condition is satisfied, the molecular aspect ratio is decreased. Specifically, as illustrated in FIG. 2, exemplified compound B-2, in which Rig in the group represented by formula [2] is an amino group, has a lower molecular aspect ratio than exemplified compound B-1, in which R₁₃ is an amino group. This can further reduce molecular association, as described in feature (2) above. When this condition is satisfied, R₁₃ can be selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted phenyl group, instead of the amino group represented by any of formulae [3-1] to [3-30].

(6) Each X₂ is a substituted or unsubstituted alkyl group.

This is because the amino group represented by any of formulae [3-1] to [3-30] is a portion responsible for the HOMO of the compound, and the introduction of an electron-donating alkyl group into this amino group is effective in increasing the electron-donating nature of the HOMO. This promotes the charge separation between the HOMO and LUMO of the compound, thereby reducing the energy difference between S₁ and T₁. In other words, as described in feature (1) above, the luminous efficiency can be improved.

X₂ can be a methyl group. This is because the energy gap between S₁ and T₁ can be reduced with a lower-molecular-weight group. Such a lower-molecular-weight compound can be used in view of sublimability and is expected to be improved in purity by purification via sublimation. Good sublimability and ease of achieving high purity enable the reduction of impurities contained in an organic light-emitting device when the device is manufactured; thus, the device characteristics should be improved.

The compound according to the embodiment can be used in a light-emitting layer of an organic light-emitting device. In this case, the following features are provided.

(7) The use of the light-emitting layer containing a mixture of the compound according to the embodiment and a host material facilitates exciton recombination of the compound according to the embodiment, thereby providing the light-emitting device with high efficiency.

(8) The use of the light-emitting layer containing a light-emitting material in addition to the mixture of the compound according to the embodiment and the host material provides the light-emitting device with high efficiency and high color purity.

(9) The use of a hydrocarbon compound as the light-emitting material provides the light-emitting device with high efficiency and good durability characteristics.

These features will be described below.

(7) The light-emitting layer containing a mixture of the compound according to the embodiment and a host material facilitates exciton recombination of the compound according to the embodiment, thereby providing the light-emitting device with high efficiency.

The compound according to the embodiment contains an electron-withdrawing carbonyl group and an electron-donating amino group as a substituent. Thus, when the compound according to the embodiment is mixed with the host material in the light-emitting layer of the organic light-emitting device, the LUMO of the compound according to the embodiment is at a lower level (farther from the vacuum level) than the host material, and the HOMO of the compound according to the embodiment is at a higher level (closer to the vacuum level) than the host material.

Accordingly, electrons and holes fed from a transport layer are trapped by the compound according to the embodiment in the light-emitting layer, and exciton recombination occurs. As described in feature (1) above, the compound according to the embodiment has a small energy difference between S₁ and T₁, can efficiently produce delayed fluorescence in the light-emitting layer, and can use a larger number of triplet excitons for light emission. This effect is especially significant when the host material is a hydrocarbon compound. The reason for this is that the larger energy difference between the HOMO and LUMO of the host and those of the compound according to the embodiment leads to easier trapping of electrons and holes. The hydrocarbon compound is a compound that consists of only carbon and hydrogen.

(8) The use of the light-emitting layer containing a light-emitting material in addition to the mixture of the compound according to the embodiment and the host material provides the light-emitting device with high efficiency and high color purity.

The use of the light-emitting layer that contains the compound according to the embodiment and that is doped with a light-emitting material having a high emission quantum yield or a light-emitting material whose emission spectrum has a spectrum suitable for exhibiting high color purity provides a light-emitting device having even higher efficiency and high color purity. In this case, the compound according to the embodiment functions as an assist material. To facilitate exciton recombination, the compound according to the embodiment needs to be contained in a concentration sufficient to preferentially trap electrons and holes in the light-emitting layer. The compound according to the embodiment is preferably 0.1% or more by mass and 45% or less by mass, more preferably 1% or more by mass and 30% or less by mass based on the entire light-emitting layer. As a light-emitting material, a smaller doping concentration is less susceptible to the influence of concentration quenching and a change in emission spectrum due to intermolecular interaction. Thus, the light-emitting layer can be doped with the light-emitting material other than the compound according to the embodiment. The doping concentration of the light-emitting material is preferably 10% or less by mass, more preferably 5% or less by mass. This provides the light-emitting device with high efficiency and high color purity.

(9) The use of a hydrocarbon compound as the light-emitting material provides the light-emitting device with high efficiency and good durability characteristics.

The compound according to the embodiment contains a strong electron-withdrawing carbonyl group. Because of this, as a light-emitting material serving as a dopant described in feature (8) above, a light-emitting material that does not contain an electron-donating amino group can be used, and a hydrocarbon compound can be used. The reason for this is that an amino group-containing light-emitting material interacts with the carbonyl group of the compound according to the embodiment in the light-emitting layer to cause a decrease in luminous efficiency due to exciplex formation and a disadvantageous change in the emission spectrum of the light-emitting material, thereby deteriorating the color purity of the light-emitting device.

Furthermore, the amino group-containing light-emitting material is easily oxidized because of its low ionization potential and thus has poor device durability. For this reason, a hydrocarbon compound can be used as a light-emitting material, and a five-membered ring-containing fused polycyclic compound can be used. This is because the structure is less susceptible to oxidation because of its higher ionization potential. The hydrocarbon compound is a compound that consists only of carbon and hydrogen in its molecule.

As described above, the use of the light-emitting layer containing the mixture of the compound according to the embodiment and the host material enables the organic light-emitting device to have high luminous efficiency. In this case, the light-emitting material may be the compound according to the embodiment. Alternatively, the light-emitting material may be another light-emitting material, and the compound according to the embodiment may function as an assist material. The use of a light-emitting material having good color purity enables the organic light-emitting device to have high efficiency and high color purity. When the host material is a hydrocarbon compound, the compound according to the embodiment can easily trap electrons and holes to contribute to higher efficiency.

While specific examples of the organic compound according to an embodiment of the present disclosure are illustrated below, the invention is not limited to these examples.

Compounds belonging to group B are each a compound in which X₁ is oxygen in the compound represented by formula [1]. Since each X₁ is oxygen, each fused polycyclic structure containing an electron-withdrawing carbonyl group is less likely to be subjected to a chemical reaction, such as oxidation. Thus, these compounds are chemically stable.

Compounds belonging to group C are each a compound in which X₁ is sulfur in the compound represented by formula [1]. Since each X₁ is sulfur, each fused polycyclic structure containing an electron-withdrawing carbonyl group is a structure having lone pairs abundantly, thus allowing the compound to have superior carrier transport ability.

Compounds belonging to group D are each a compound in which X₁ is a CR₉R₁₀ group in the compound represented by formula [1]. Since each X₁ is CR₉R₁₀, these compounds are superior in reducing molecular association. Thus, the compounds are less likely to undergo concentration quenching.

Compounds belonging to group E are each a compound in which X₁ is selenium or tellurium in the compound represented by formula [1]. Each of selenium and tellurium is an element having a d-orbital and metallic properties. Thus, the compounds belonging to group E have high carrier mobility.

The organic compound according to the embodiment has high luminous efficiency and superior film properties. Accordingly, the use of the organic compound according to the embodiment as a component material for an organic light-emitting device enables the organic light-emitting device to have good emission characteristics and superior durability characteristics.

Organic Light-Emitting Device

The organic light-emitting device according to the embodiment will be described below.

The organic light-emitting device according to the embodiment at least includes an anode and a cathode, which are a pair of electrodes, and an organic compound layer disposed between these electrodes. In the organic light-emitting device according to the embodiment, the organic compound layer may be formed of a single layer or a multilayer stack including multiple layers, as long as it includes a light-emitting layer. When the organic compound layer is formed of a multilayer stack including multiple layers, the organic compound layer may include, in addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron-blocking layer, a hole/exciton-blocking layer, an electron transport layer, and an electron injection layer, for example. The light-emitting layer may be formed of a single layer or a multilayer stack including multiple layers.

In the organic light-emitting device according to the embodiment, at least one organic compound layer contains the organic compound according to the embodiment. Specifically, the organic compound according to the embodiment is contained in any of the light-emitting layer, the hole injection layer, the hole transport layer, the electron-blocking layer, the hole/exciton-blocking layer, the electron transport layer, the electron injection layer, and so forth. The organic compound according to the embodiment can be contained in the light-emitting layer. The light-emitting layer can emit green light or red light. The emission color is not limited thereto.

In the organic light-emitting device according to the embodiment, when the organic compound according to the embodiment is contained in the light-emitting layer, the light-emitting layer may consist of only the organic compound according to the embodiment or may be composed of the organic compound according to the embodiment and another compound. When the light-emitting layer is composed of the organic compound according to the embodiment and another compound, the organic compound according to the embodiment may be used as a host or a guest in the light-emitting layer. The organic compound may be used as an assist material that can be contained in the light-emitting layer. The term “host” used here refers to a compound having the highest proportion by mass in compounds contained in the light-emitting layer. The term “guest” refers to a compound that has a lower proportion by mass than the host in the compounds contained in the light-emitting layer and that is responsible for main light emission. The term “assist material” refers to a compound that has a lower proportion by mass than the host in the compounds contained in the light-emitting layer and that assists the light emission of the guest.

When the organic compound according to the embodiment is used as a guest in the light-emitting layer, the concentration of the guest is preferably 0.01% or more by mass and 20% or less by mass, more preferably 1% or more by mass and 15% or less by mass, based on the entire light-emitting layer. When the organic compound according to the embodiment is used as an assist material in the light-emitting layer, the concentration of the assist material is preferably 0.1% or more by mass and 45% or less by mass, more preferably 1% or more by mass and 30% or less by mass, based on the entire light-emitting layer.

When the organic compound according to the embodiment is used as a guest in the light-emitting layer, a material having a higher LUMO level than the organic compound according to the embodiment (a material having a LUMO level closer to the vacuum level) can be used as a host. The organic compound according to the embodiment contains a carbonyl group and thus has a low LUMO level (farther from the vacuum level). Thus, when the organic compound according to the embodiment is used in the light-emitting layer, the LUMO relationship as described above is easily formed. This is because when a material having a higher LUMO level than the organic compound according to the embodiment is used as a host, the organic compound according to the embodiment can receive more electrons supplied to the host of the light-emitting layer.

In the case where the organic compound according to the embodiment is used as an assist material in the light-emitting layer, a material having a higher LUMO level than the organic compound according to the embodiment (a material having a LUMO level closer to the vacuum level) can be used as a guest. The organic compound according to the embodiment contains a carbonyl group and thus has a low LUMO level (farther from the vacuum level). Thus, when the organic compound according to the embodiment is used in the light-emitting layer, the LUMO relationship as described above is easily formed. Thus, when a material having a higher LUMO level than the organic compound according to the embodiment is used as a guest serving as a light-emitting material, the organic compound according to the embodiment receives more electrons supplied to the host of the light-emitting layer, and the assist material is responsible for exciton recombination.

This enables efficient energy transfer to the guest serving as a light-emitting material.

The inventors have conducted various studies and have found that when the organic compound according to the embodiment is used as a host, guest, or assist material of a light-emitting layer, especially as a guest of a light-emitting layer, a device that emits light with high efficiency and high luminance, and is extremely durable can be provided. The inventors have further found that when the organic compound according to the embodiment is used as an assist material in the light-emitting layer, a device that emits light with high efficiency and high luminance, and is extremely durable can be provided. The light-emitting layer may be formed of a single layer or multiple layers, and can contain multiple light-emitting materials. The term “multiple layers” may include a state in which the light-emitting layer and another light-emitting layer are stacked, or a state in which an intermediate layer is stacked between multiple light-emitting layers. Tandem or stacked devices are also acceptable. In these cases, the emission color of the organic light-emitting device is not limited to a single color. More specifically, the emission color may be white or an intermediate color. A film-forming method is vapor deposition or coating. Details will be described in examples below.

The organic compound according to the embodiment can be used as a component material of an organic compound layer other than the light-emitting layer included in the organic light-emitting device according to the embodiment. Specifically, the organic compound may be used as a component material of the electron transport layer, the electron injection layer, the hole transport layer, the hole injection layer, the hole blocking layer, and so forth.

For example, a hole injection compound, a hole transport compound, a compound to be used as a host, a light-emitting compound, an electron injection compound, or an electron transport compound, which is known and has a low or high molecular weight, can be used together with the organic compound according to the embodiment, as needed. Examples of these compounds will be described below.

As a hole injection-transport material, a material having a high hole mobility can be used so as to facilitate the injection of holes from the anode and to transport the injected holes to the light-emitting layer. To reduce a deterioration in film quality, such as crystallization, in the organic light-emitting device, a material having a high glass transition temperature can be used. Examples of a low- or high-molecular-weight material having the ability to inject and transport holes include triarylamine derivatives, aryl carbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinyl carbazole), polythiophene, and other conductive polymers. Moreover, the hole injection-transport material can be used for the electron-blocking layer. Non-limiting specific examples of a compound used as the hole injection-transport material will be illustrated below.

Among the hole transport materials illustrated above, HT16 to HT18 can be used in the layer in contact with the anode to reduce the driving voltage. HT16 is widely used in organic light-emitting devices. HT2, HT3, HT4, HT5, HT6, HT10, and HT12 may be used in an organic compound layer adjacent to HT16. Multiple materials may be used in a single organic compound layer.

Examples of a light-emitting material mainly associated with a light-emitting function include, in addition to the organic compounds according to the embodiment, fused-ring compounds, such as fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene compounds, and rubrene, quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes, such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives, such as poly(phenylene vinylene) derivatives, polyfluorene derivatives, and polyphenylene derivatives. Non-limiting specific examples of a compound used as a light-emitting material are illustrated below.

When the light-emitting material is a hydrocarbon compound, the material can prevent a decrease in luminous efficiency due to exciplex formation and a deterioration in color purity due to a change in the emission spectrum of the light-emitting material. The hydrocarbon compound is a compound consisting of only carbon and hydrogen. BD7, BD8, GD5 to GD9, and RD1 are hydrocarbon compounds. When the light-emitting material is a fused polycyclic compound containing a five-membered ring, the material has a high ionization potential and high resistance to oxidation. This can provide a highly durable device with a long lifetime. BD7, BD8, GD5 to GD9, and RD1 are five-membered ring-containing fused polycyclic compounds.

Examples of a host or an assist material in the light-emitting layer include aromatic hydrocarbon compounds and derivatives thereof, carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes, such as tris(8-quinolinolato)aluminum, and organoberyllium complexes. Non-limiting specific examples of a compound used as a host or an assist material in the light-emitting layer will be illustrated below.

When the host material is a hydrocarbon compound, the compound according to the embodiment can easily trap electrons and holes to contribute to higher efficiency. The term “hydrocarbon compound” refers to a compound consisting of only carbon and hydrogen, and EM1 to EM12 and EM16 to EM27 are hydrocarbon compounds.

The electron transport material can be freely-selected from materials capable of transporting electrons injected from the cathode to the light-emitting layer and is selected in consideration of, for example, the balance with the hole mobility of the hole transport material. Examples of a material having the ability to transport electrons include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and condensed-ring compounds, such as fluorene derivatives, naphthalene derivatives, chrysene derivatives, and anthracene derivatives. The electron transport materials can be used for the hole-blocking layer. Non-limiting specific examples of a compound used as the electron transport material will be illustrated below.

An electron injection material can be freely-selected from materials capable of easily injecting electrons from the cathode and is selected in consideration of, for example, the balance with the hole-injecting properties. As the organic compound, n-type dopants and reducing dopants are also included. Examples thereof include alkali metal-containing compounds, such as lithium fluoride, lithium complexes, such as lithium quinolinolate, benzimidazolidene derivatives, imidazolidene derivatives, fulvalene derivatives, and acridine derivatives.

Configuration of Organic Light-Emitting Device

The organic light-emitting device is provided by disposing an anode, the organic compound layer, and a cathode on a substrate. A protective layer, a color filter, and so forth may be disposed on or above the cathode. In the case of disposing the color filter, a planarization layer may be disposed between the protective layer and the color filter. The planarization layer can be composed of, for example, an acrylic resin.

Substrate

Examples of the substrate include silicon wafers, quartz substrates, glass substrates, resin substrates, and metal substrates. The substrate may include a switching element, such as a transistor, a line, and an insulating layer thereon. As the insulating layer, any material can be used as long as a contact hole can be formed to establish the electrical connection between the anode and the line and as long as insulation with a non-connected line can be ensured. For example, a resin such as polyimide, silicon oxide, or silicon nitride can be used.

Electrode

A pair of electrodes can be used. The pair of electrodes may be an anode and a cathode.

In the case where an electric field is applied in the direction in which the organic light-emitting device emits light, an electrode having a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode and that the electrode that supplies electrons is the cathode.

As the constituent material of the anode, a material having a work function as high as possible can be used. Examples of the material that can be used include elemental metals, such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, mixtures thereof, alloys of combinations thereof, and metal oxides, such as tin oxide, zinc oxide, indium oxide, indium-tin oxide (ITO), and indium-zinc oxide. Additionally, conductive polymers, such as polyaniline, polypyrrole, and polythiophene, may be used.

These electrode materials may be used alone or in combination of two or more. The anode may be formed of a single layer or multiple layers.

In the case where the anode is used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, an alloy thereof, or a stack thereof may be used. In the case where the anode is used as a transparent electrode, a transparent conductive oxide layer composed of, for example, indium-tin oxide (ITO) or indium-zinc oxide may be used; however, the anode is not limited thereto. The electrodes may be formed by photolithography.

As the constituent material of the cathode, a material having a lower work function can be used. Examples thereof include elemental metals such as alkali metals, e.g., lithium, alkaline-earth metals, e.g., calcium, aluminum, titanium, manganese, silver, lead, and chromium, and mixtures thereof. Alloys of combinations of these elemental metals may also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver may be used. Metal oxides such as indium-tin oxide (ITO) may also be used. These electrode materials may be used alone or in combination of two or more. The cathode may have a single-layer structure or a multilayer structure. In particular, silver can be used. To reduce the aggregation of silver, a silver alloy can be used. Any alloy ratio may be used as long as the aggregation of silver can be reduced. The ratio of silver to another metal may be, for example, 1:1.

A top emission device may be provided using the cathode formed of a conductive oxide layer composed of, for example, ITO. A bottom emission device may be provided using the cathode formed of a reflective electrode composed of, for example, aluminum (Al). The cathode is not particularly limited. Any method for forming the cathode may be used. For example, a direct-current or alternating-current sputtering technique can be employed because good film coverage is obtained and thus the resistance is easily reduced.

Protective Layer

A protective layer may be disposed on the cathode. For example, a glass member provided with a moisture absorbent can be bonded to the cathode to reduce the entry of, for example, water into the organic compound layer, thereby suppressing the occurrence of display defects. In another embodiment, a passivation film composed of, for example, silicon nitride may be disposed on the cathode to reduce the entry of, for example, water into the organic compound layer. For example, after the formation of the cathode, the substrate may be transported to another chamber without breaking the vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by a chemical vapor deposition (CVD) method to provide a protective layer. After the film deposition by the CVD method, a protective layer may be formed by an atomic layer deposition (ALD) method.

Color Filter

A color filter may be disposed on the protective layer. For example, a color filter may be disposed on another substrate in consideration of the size of the organic light-emitting device and bonded to the substrate provided with the organic light-emitting device. A color filter may be formed by patterning on the protective layer using photolithography. The color filter may be composed of a polymer.

Planarization Layer

A planarization layer may be disposed between the color filter and the protective layer. The planarization layer may be composed of an organic compound. A low- or high-molecular-weight organic compound may be used. A high-molecular-weight organic compound can be used.

The planarization layer may be provided on each of the top and bottom of the color filter. In this case, the planarization layers may be composed of the same material or different materials. Specific examples thereof include poly(vinyl carbazole) resins, polycarbonate resins, polyester resins, acrylonitrile butadiene styrene (ABS) resins, acrylic resins, polyimide resins, phenolic resins, epoxy resins, silicone resins, and urea resins.

Opposite Substrate

An opposite substrate may be disposed on the planarization layer. The opposite substrate is disposed at a position corresponding to the substrate described above and thus is called an opposite substrate. The opposite substrate may be composed of the same material as the substrate described above.

Organic Layer

The organic compound layer, such as the hole injection layer, the hole transport layer, the electron-blocking layer, the light-emitting layer, the hole-blocking layer, the electron transport layer, or the electron injection layer, included in the organic light-emitting device according to an embodiment of the present disclosure is formed by a method described below.

For the organic compound layer included in the organic light-emitting device according to an embodiment of the present disclosure, a dry process, such as a vacuum evaporation method, an ionized evaporation method, sputtering, or plasma, may be employed. Alternatively, instead of the dry process, it is also possible to employ a wet process in which a material is dissolved in an appropriate solvent and then a film is formed by a known coating method, such as spin coating, dipping, a casting method, a Langmuir-Blodgett (LB) technique, or an ink jet method.

In the case where the layer is formed by, for example, the vacuum evaporation method or the solution coating method, crystallization and so forth are less likely to occur, and good stability with time is obtained. In the case of forming a film by the coating method, the film may be formed in combination with an appropriate binder resin.

Non-limiting examples of the binder resin include poly(vinyl carbazole) resins, polycarbonate resins, polyester resins, acrylonitrile butadiene styrene (ABS) resins, acrylic resins, polyimide resins, phenolic resins, epoxy resins, silicone resins, and urea resins.

These binder resins may be used alone as a homopolymer or copolymer or in combination as a mixture of two or more. Furthermore, additives, such as a known plasticizer, antioxidant, and ultraviolet absorber, may be used, as needed.

Application of Organic Light-Emitting Device According to Embodiment of the Present Disclosure

The organic light-emitting device according to an embodiment can be used as component member of a display apparatus or a lighting apparatus. Other applications include exposure light sources for electrophotographic image-forming apparatuses, backlights for liquid crystal displays, and light-emitting devices including white light sources and color filters.

The display apparatus may be an image information-processing unit having an image input unit that receives image information from an area or linear CCD sensor, a memory card, or any other source, an information-processing unit that processes the input information, and a display unit that displays the input image. The display apparatus includes multiple pixels, and at least one of the multiple pixels may include the organic light-emitting device according to the embodiment and a transistor coupled to the organic light-emitting device.

The display unit of an image pickup apparatus or an inkjet printer may have a touch panel function. The driving mode of the touch panel function may be, but is not particularly limited to, an infrared mode, an electrostatic capacitance mode, a resistive film mode, or an electromagnetic inductive mode. The display apparatus may also be used for a display unit of a multifunction printer.

The following describes a display apparatus according to the embodiment with reference to the attached drawings. FIG. 3 is a schematic cross-sectional view of an example of a display apparatus including organic light-emitting devices and thin-film transistor (TFT) elements coupled to the respective organic light-emitting devices. Each of the TFT elements is an example of active elements.

A display apparatus 10 illustrated in FIG. 3 includes a substrate 11 composed of, for example, glass and a moisture-proof film 12 disposed thereon, the moisture-proof film 12 being configured to protect TFT elements or the organic compound layers. Reference numeral 13 denotes a gate electrode of a metal. Reference numeral 14 denotes a gate insulating film. Reference numeral 15 denotes a semiconductor layer.

TFT elements 18 each include the semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is disposed on the TFT elements 18. An anode 21 included in an organic light-emitting device 26 is coupled to the source electrode 17 through a contact hole 20.

The way of electric coupling between the electrodes (the anode 21 and a cathode 23) included in each of the organic light-emitting devices 26 and the electrodes (the source electrode 17 and the drain electrode 16) included in a corresponding one of the TFT elements 18 is not limited to the configuration illustrated in FIG. 3. It is sufficient that one of the anode 21 and the cathode 23 is electrically coupled to one of the source electrode 17 and the drain electrode 16 of the TFT element 18.

In the display apparatus 10 illustrated in FIG. 3, each organic compound layer 22 is illustrated as a single layer; however, the organic compound layer 22 may be formed of multiple layers. To reduce the deterioration of the organic light-emitting devices 26, a first protective layer 24 and a second protective layer 25 are disposed on the cathodes 23.

In the display apparatus 10 illustrated in FIG. 3, the transistors are used as switching elements; however, metal-insulator-metal (MIM) elements may also be used as switching elements instead.

The transistors used in the display apparatus 10 illustrated in FIG. 3 are not limited to transistors formed using a single-crystal silicon wafer and may be thin-film transistors each having an active layer on the insulating surface of a substrate. Examples of the material of the active layer include single-crystal silicon, non-single-crystal silicon materials, such as amorphous silicon and microcrystalline silicon, and non-single-crystal oxide semiconductors, such as indium-zinc oxide and indium-gallium-zinc oxide. Thin-film transistors are also called TFT elements.

The transistors in the display apparatus 10 illustrated in FIG. 3 may be formed in the substrate such as a Si substrate. The expression “formed in the substrate” indicates that the transistors are produced by processing the substrate such as a Si substrate. In the case where the transistors are formed in the substrate, the substrate and the transistors can be deemed to be integrally formed.

In the organic light-emitting device according to the embodiment, the luminance is controlled by the TFTs, which are an example of switching elements; thus, an image can be displayed at respective luminance levels by arranging multiple organic light-emitting devices in the plane. The switching elements according to the embodiment are not limited to the TFT elements and may be low-temperature polysilicon transistors or active-matrix drivers formed on a substrate such as a Si substrate. The expression “on a substrate” can also be said to be “in the substrate”. Whether transistors are formed in the substrate or TFTs are used is selected in accordance with the size of a display unit. For example, in the case where the display unit has a size of about 0.5 inches, organic light-emitting devices can be disposed on a Si substrate.

FIG. 4 is a schematic view illustrating an example of a display apparatus according to the embodiment. A display apparatus 1000 may include a touch screen 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 disposed between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are coupled to flexible printed circuits FPCs 1002 and 1004, respectively. The circuit board 1007 includes printed transistors. The battery 1008 need not be provided unless the display apparatus is a portable apparatus. The battery 1008 may be disposed at a different position even if the display apparatus is a portable apparatus.

The display apparatus according to the embodiment may be used for a display unit of a photoelectric conversion apparatus, such as an image pickup apparatus including an optical unit including multiple lenses and an image pickup device that receives light passing through the optical unit.

The image pickup apparatus may include a display unit that displays information acquired by the image pickup device. The display unit may be a display unit exposed to the outside of the image pickup apparatus or a display unit disposed in a finder. The image pickup apparatus may be a digital camera or a digital camcorder. The image pickup apparatus may also be referred to as a photoelectric conversion apparatus.

FIG. 5A is a schematic view illustrating an example of an image pickup apparatus according to the embodiment. An image pickup apparatus 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may include the display apparatus according to the embodiment. In this case, the display apparatus may display environmental information, imaging instructions, and so forth in addition to an image to be captured. The environmental information may include, for example, the intensity of external light, the direction of the external light, the moving speed of a subject, and the possibility that a subject is shielded by a shielding material.

The timing suitable for imaging is only for a short time; thus, the information may be displayed as soon as possible. Accordingly, the display apparatus including the organic light-emitting device according to the embodiment can be used because of its short response time. The display apparatus including the organic light-emitting device can be used more suitably than liquid crystal displays for these units required to have a high display speed.

The image pickup apparatus 1100 includes an optical unit (not illustrated). The optical unit includes multiple lenses and is configured to form an image on an image pickup device in the housing 1104. The relative positions of the multiple lenses can be adjusted to adjust the focal point. This operation can also be performed automatically.

The display apparatus according to the embodiment may include a color filter having red, green, and blue portions. In the color filter, the red, green, and blue portions may be arranged in a delta arrangement.

A display apparatus according to the embodiment may be used for a display unit of an electronic apparatus, such as a portable terminal. In that case, the display apparatus may have both a display function and an operation function. Examples of the portable terminal include cellular phones, such as smartphones, tablets, and head-mounted displays.

FIG. 5B is a schematic view illustrating an example of an electronic apparatus according to the embodiment. An electronic apparatus 1200 includes a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may accommodate a circuit, a printed circuit board including the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch-panel-type reactive unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint to release the lock or the like. An electronic apparatus having a communication unit can also be referred to as a communication apparatus.

FIG. 6A is a schematic view illustrating an example of the display apparatus according to the embodiment. FIG. 6A illustrates a display apparatus, such as a television monitor or a PC monitor. A display apparatus 1300 includes a frame 1301 and a display unit 1302. The display unit 1302 may include an organic electroluminescent element according to the embodiment. The display apparatus 1300 also includes a base 1303 that supports the frame 1301 and the display unit 1302. The base 1303 is not limited to the structure illustrated in FIG. 6A. The lower side of the frame 1301 may also serve as a base. The frame 1301 and the display unit 1302 may be curved. These may have a radius of curvature of 5,000 mm or more and 6,000 mm or less.

FIG. 6B is a schematic view illustrating another example of a display apparatus according to the embodiment. A display apparatus 1310 illustrated in FIG. 6B can be folded and is what is called a foldable display apparatus. The display apparatus 1310 includes a first display portion 1311, a second display portion 1312, a housing 1313, and an inflection point 1314. The first display portion 1311 and the second display portion 1312 may include light-emitting devices according to the embodiment. The first display portion 1311 and the second display portion 1312 may be a single, seamless display apparatus. The first display portion 1311 and the second display portion 1312 can be divided from each other at the inflection point. The first display portion 1311 and the second display portion 1312 may display different images from each other. Alternatively, a single image may be displayed in the first and second display portions.

FIG. 7A is a schematic view illustrating an example of a lighting apparatus according to the embodiment. A lighting apparatus 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical filter 1404 that transmits light emitted from the light source 1402, and a light diffusion unit 1405. The light source 1402 may include an organic light-emitting device according to the embodiment. The optical filter 1404 may be a filter that improves the color rendering properties of the light source. The light diffusion unit 1405 can effectively diffuse light from the light source to deliver the light to a wide range when used for illumination and so forth. The optical filter 1404 and the light diffusion unit 1405 may be disposed at the light emission side of the lighting apparatus. A cover may be disposed at the outermost portion, as needed.

The lighting apparatus is, for example, an apparatus that lights a room. The lighting apparatus may emit light of white, neutral white, or any color from blue to red. A light control circuit that controls the light may be provided.

The lighting apparatus may include the organic light-emitting device according to the embodiment and a power supply circuit coupled thereto. The power supply circuit is a circuit that converts an AC voltage into a DC voltage. The color temperature of white is 4,200 K, and the color temperature of neutral white is 5,000 K. The lighting apparatus may include a color filter.

The lighting apparatus according to the embodiment may include a heat dissipation unit. The heat dissipation unit is configured to release heat in the device to the outside of the device and is composed of, for example, a metal having a high specific heat and liquid silicone.

FIG. 7B is a schematic view illustrating an automobile, as an example of a moving object, according to the embodiment. The automobile includes a tail lamp, which is an example of lighting units. An automobile 1500 includes a tail lamp 1501 and may be configured to light the tail lamp when a brake operation or the like is performed.

The tail lamp 1501 may include an organic light-emitting device according to the embodiment. The tail lamp 1501 may include a protective member that protects the organic light-emitting device. The protective member may be composed of any transparent material having high strength to some extent and can be composed of, for example, polycarbonate. The polycarbonate may be mixed with, for example, a furandicarboxylic acid derivative or an acrylonitrile derivative.

The automobile 1500 may include an automobile body 1503 and windows 1502 attached thereto. The windows 1502 may be transparent displays if the windows are not used to check the front and back of the automobile. The transparent displays may include an organic light-emitting device according to the embodiment.

In this case, the components, such as the electrodes, of the organic light-emitting device are formed of transparent members.

The moving object according to the embodiment may be, for example, a ship, an aircraft, or a drone. The moving object may include a body and a lighting unit attached to the body. The lighting unit may emit light to indicate the position of the body. The lighting unit includes the organic light-emitting device according to the embodiment.

Exemplary applications of the display apparatuses of the above embodiments will be described with reference to FIGS. 8A and 8B. The display apparatuses can be used for systems that can be worn as wearable devices, such as smart glasses, head-mounted displays (HMDs), and smart contacts. An image pickup and display apparatus used in such an application has an image pickup apparatus that can photoelectrically convert visible light and a display apparatus that can emit visible light.

FIG. 8A is a schematic view illustrating an example of a wearable device according to an embodiment of the present disclosure. Glasses 1600 (smart glasses) according to an example of applications will be described with reference to FIG. 8A. An image pickup apparatus 1602, such as a complementary metal-oxide semiconductor (CMOS) sensor or a single-photon avalanche diode (SPAD), is provided on a front side of a lens 1601 of the glasses 1600. The display apparatus according to any of the above-mentioned embodiments is provided on the back side of the lens 1601.

The glasses 1600 further include a control unit 1603. The control unit 1603 functions as a power source that supplies electric power to the image pickup apparatus 1602 and the display apparatus. The control unit 1603 controls the operation of the image pickup apparatus 1602 and the display apparatus. The lens 1601 has an optical system for focusing light on the image pickup apparatus 1602.

FIG. 8B is a schematic view of another example of a wearable device according to an embodiment of the present disclosure. Glasses 1610 (smart glasses) according to an example of applications will be described with reference to FIG. 8B. The glasses 1610 include a control unit 1612. The control unit 1612 includes an image pickup apparatus corresponding to the image pickup apparatus 1602 illustrated in FIG. 8A and a display apparatus. A lens 1611 is provided with the image pickup apparatus in the control unit 1612 and an optical system that projects light emitted from the display apparatus. An image is projected onto the lens 1611. The control unit 1612 functions as a power source that supplies electric power to the image pickup apparatus and the display apparatus and controls the operation of the image pickup apparatus and the display apparatus.

The control unit 1612 may include a gaze detection unit that detects the gaze of a wearer. Infrared light may be used for gaze detection. An infrared light-emitting unit emits infrared light to an eyeball of a user who is gazing at a displayed image. An image of the eyeball is captured by detecting the reflected infrared light from the eyeball with an image pickup unit having light-receiving elements. The deterioration of image quality is reduced by providing a reduction unit that reduces light from the infrared light-emitting unit to the display unit when viewed in plan. The user's gaze at the displayed image is detected from the image of the eyeball captured with the infrared light. Any known method can be employed to the gaze detection using the captured image of the eyeball. As an example, a gaze detection method based on a Purkinje image of the reflection of irradiation light on a cornea can be employed. More specifically, the gaze detection process is based on a pupil-corneal reflection method. Using the pupil-corneal reflection method, the user's gaze is detected by calculating a gaze vector representing the direction (rotation angle) of the eyeball based on the image of the pupil and the Purkinje image contained in the captured image of the eyeball.

A display apparatus according to an embodiment of the present disclosure may include an image pickup apparatus including light-receiving elements, and may control an image displayed on the display apparatus based on the gaze information of the user from the image pickup apparatus. Specifically, in the display apparatus, a first field of view at which the user gazes and a second field of view other than the first field of view are determined on the basis of the gaze information. The first field of view and the second field of view may be determined by the control unit of the display apparatus or may be determined by receiving those determined by an external control unit. In the display area of the display apparatus, the display resolution of the first field of view may be controlled to be higher than the display resolution of the second field of view. That is, the resolution of the second field of view may be lower than that of the first field of view.

The display area includes a first display area and a second display area different from the first display area. Based on the gaze information, an area of higher priority is determined from the first display area and the second display area. The first display area and the second display area may be determined by the control unit of the display apparatus or may be determined by receiving those determined by an external control unit. The resolution of an area of higher priority may be controlled to be higher than the resolution of an area other than the area of higher priority. In other words, the resolution of an area of a relatively low priority may be low.

Artificial intelligence (AI) may be used to determine the first field of view or the high-priority area. The AI may be a model configured to estimate the angle of gaze from the image of the eyeball and the distance to a target object located in the gaze direction, using the image of the eyeball and the actual direction of gaze of the eyeball in the image as teaching data. The AI program may be stored in the display apparatus, the image pickup apparatus, or an external apparatus. When the AI program is stored in the external apparatus, the AI program is transmitted to the display apparatus via communications.

In the case of controlling the display based on visual detection, smart glasses that further include an image pickup apparatus that captures an external image can be used. The smart glasses can display the captured external information in real time.

FIG. 9A is a schematic view of an example of an image-forming apparatus according to the embodiment. An image-forming apparatus 40 is an electrophotographic image-forming apparatus and includes a photoconductor 27, an exposure light source 28, a charging unit 30, a developing unit 31, a transfer unit 32, a transport roller 33, and a fixing unit 35. Light 29 is emitted from the exposure light source 28 to form an electrostatic latent image on the surface of the photoconductor 27. The exposure light source 28 includes the organic light-emitting device according to the embodiment. The developing unit 31 contains, for example, a toner. The charging unit 30 charges the photoconductor 27. The transfer unit 32 transfers the developed image to a recording medium 34. The transport roller 33 transports the recording medium 34. The recording medium 34 is paper, for example. The fixing unit 35 fixes the image formed on the recording medium 34.

FIGS. 9B and 9C illustrate the exposure light source 28 and are each a schematic view illustrating multiple light-emitting portions 36 arranged on a long substrate. Arrows 37 each represent the row direction in which the organic light-emitting devices are arranged. The row direction is the same as the direction of the axis on which the photoconductor 27 rotates. This direction can also be referred to as the long-axis direction of the photoconductor 27. FIG. 9B illustrates a configuration in which the light-emitting portions 36 are arranged in the long-axis direction of the photoconductor 27. FIG. 9C is different from FIG. 9B in that the light-emitting portions 36 are arranged alternately in the row direction in a first row and a second row. The first row and the second row are located at different positions in the column direction. In the first row, the multiple light-emitting portions 36 are spaced apart. The second row has the light-emitting portions 36 at positions corresponding to the positions between the light-emitting portions 36 in the first row. In other words, the multiple light-emitting portions 36 are also spaced apart in the column direction. The arrangement in FIG. 9C can be rephrased as, for example, a lattice arrangement, a staggered arrangement, or a checkered pattern.

As described above, the use of an apparatus including the organic light-emitting device according to the embodiment enables a stable display with good image quality even for a long time.

EXAMPLES

The present disclosure will be described below by examples. The present disclosure, however, is not limited to the following examples.

Example 1: Synthesis of Exemplified Compound B-1

Exemplified compound B-1 was synthesized according to the following scheme.

(1) Synthesis of Compound m-3

The following reagents and solvents were placed in a 500-mL recovery flask.

Compound m-1: 5.0 g (18.2 mmol) Compound m-2: 3.4 g (21.8 mmol) Sodium carbonate: 15.1 g (10.9 mmol)

Toluene: 150 mL

Deionized water: 75 mL

Ethanol: 150 mL

Pd(PPh₃)₄: 210 mg

The reaction solution was heated and stirred at 100° C. for 7 hours under a stream of nitrogen. After the completion of the reaction, 100 mL of water was added, and then the mixture was filtered. The resulting solid was purified by silica gel column chromatography (toluene-ethyl acetate mixture) to give 4.5 g of m-3 (yield: 81%).

(2) Synthesis of Compound B-1

The following reagents and solvent were placed in a 200-mL recovery flask.

Compound m-3: 1.5 g (4.9 mmol) Compound m-4: 1.2 g (5.9 mmol) Sodium tert-butoxide: 1.41 g (14.7 mmol)

Pd(dba)₂: 280 mg Xphos: 700 mg

o-Xylene: 75 mL

The reaction solution was heated and stirred at 140° C. for 5 hours under a stream of nitrogen. After the completion of the reaction, filtration was performed through Celite, and then the filtrate was concentrated to dryness. The resulting solid was purified by silica gel column chromatography (toluene-ethyl acetate mixture) to give 1.3 g of B-1 (yield: 59%).

Exemplified compound B-1 was subjected to mass spectrometry with MALDI-TOF-MS (Bruker Autoflex LRF).

[MALDI-TOF-MS]

Measured value: m/z=465 Calculated value: C₃₃H₂₃NO₂=465

Examples 2 to 16: Synthesis of Exemplified Compounds

As presented in Table 1, exemplified compounds of Examples 2 to 16 were each synthesized as in Example 1, except that raw material m-1 in Example 1 was changed to raw material 1, raw material m-2 was changed to raw material 2, and raw material m-4 was changed to raw material 3. The resulting exemplified compounds were subjected to mass spectrometry as in Example 1. The measured values (m/z) are presented below.

TABLE 1 Ex- em- pli- Ex- fied am- com- ple pound Raw material 1 Raw material 2 Raw material 3 m/z 2 B-2 

465 3 B-7 

665 4 B-10

521 5 B-27

598 6 C-1 

497 7 C-4 

523 8 C-6 

632 9 C-11

633 10 C-18

635 11 C-21

558 12 D-1 

627 13 D-2 

593 14 D-6 

607 15 D-13

615 16 D-14

592

Example 17

In this Example, an organic light-emitting device having a bottom-emission structure was produced in which an anode, a hole injection layer, a hole transport layer, an electron-blocking layer, a light-emitting layer, a hole-blocking layer, an electron transport layer, an electron injection layer, and a cathode were sequentially formed on a substrate.

An ITO film was formed on a glass substrate and subjected to desired patterning to form an ITO electrode (anode). The ITO electrode had a thickness of 100 nm. The substrate on which the ITO electrode had been formed in this way was used as an ITO substrate in the following steps. Next, vapor deposition was performed by resistance heating in a vacuum chamber to continuously form organic compound layers and an electrode layer presented in Table 2 on the ITO substrate. Here, the opposing electrode (metal electrode layer, cathode) had an electrode area of 3 mm². The “percentage (%)” in Table 2 is percentage by mass.

TABLE 2 Material Thickness (nm) Cathode Al 100 Electron injection layer (EIL) LiF 1 Electron transport layer (ETL) ET2 15 Hole-blocking layer (HBL) ET11 15 light-emitting host material Light emitting layer (EML) EM11 B-1 20 Light-emitting layer, 88 12 percentage (%) Electron-blocking layer (EBL) HT12 15 Hole transport layer (HTL) HT2 30 Hole injection layer (HIL) HT16 5

The characteristics of the resulting device were measured and evaluated. As the initial characteristics of the light emission, green light emission with a maximum external quantum efficiency (E.Q.E.) of 5.0% was obtained. With regard to measurement instruments, specifically, the current-voltage characteristics were measured with a Hewlett-Packard 4140B microammeter, and the luminance was measured with a Topcon BM7. The device was subjected to a continuous operation test at a current density of 50 mA/cm². The time when the percentage of luminance degradation reached 5% (LT95) was measured and found to be 105 hours.

Examples 18 to 22

Organic light-emitting devices were produced in the same manner as Example 17, except that the compounds used in Example 17 were changed to compounds listed in Table 3 as appropriate. The characteristics of the resulting device were measured and evaluated as in Example 17. Table 3 presents the measurement results.

TABLE 3 EML Light- emitting E.Q.E LT95 Emission HTL EBL Host material HBL ETL [%] [h] color Example 18 HT3 HT12 EM11 B-2 ET12 ET2 5.5 110 green Example 19 HT3 HT11 EM11 B-7 ET12 ET2 5.4 83 green Example 20 HT3 HT12 EM11 C-4 ET12 ET2 5.5 115 green Example 21 HT2 HT11 EMU D-2 ET12 ET2 5.6 105 green Example 22 HT2 HT10 EM32 D-6 ET12 ET5 5.6 79 green

Example 23

An organic light-emitting device was produced in the same manner as in Example 17, except that the organic compound layers and the electrode layer listed in Table 4 were continuously deposited. The “percentage (%)” in Table 4 is percentage by mass.

TABLE 4 Material Thickness (nm) Cathode Al 100 Electron injection layer (EIL) LiF 1 Electron transport layer (ETL) ET2 15 Hole-blocking layer (HBL) ET11 15 assist light-emitting host material material Light-emitting layer (EML) EM11 B-1 GD5 20 Light-emitting layer, 82 15 3 percentage (%) Electron-blocking layer (EBL) HT7 15 Hole transport layer (HTL) HT3 30 Hole injection layer (HIL) HT16 5

The characteristics of the resulting device were measured and evaluated in the same way as in Example 17. As the initial characteristics of the light emission, green light emission with a maximum external quantum efficiency (E.Q.E.) of 6.3% was obtained. The device was subjected to a continuous operation test at a current density of 50 mA/cm². The time when the percentage of luminance degradation reached 5% (LT95) was measured and found to be 136 hours.

Examples 24 to 41 and Comparative Examples 1 and 2

Organic light-emitting devices were produced in the same manner as in Example 23, except that the compounds used in Example 23 were changed to compounds listed in Table 5 as appropriate. The characteristics of the resulting device were measured and evaluated in the same way as in Example 23. Table 5 presents the measurement results. Comparative compound 1 is comparative compound 1 illustrated in FIGS. 1 and 2. Comparative compound 2 is comparative compound 2 illustrated in FIG. 1.

TABLE 5 EML Light- emitting E.Q.E LT95 Emission HTL EBL Host Assist material HBL ETL [%] [h] color Example 24 HT3 HT12 EM11 B-2 GD5 ET12 ET2 6.2 151 green Example 25 HT3 HT11 EM11 B-10 GD5 ET12 ET2 6.4 132 green Example 26 HT3 HT12 EM11 C-1 GD6 ET12 ET2 6.5 129 green Example 27 HT2 HT11 EM14 C-6 GD6 ET12 ET2 6.5 155 green Example 28 HT2 HT10 EM14 C-18 GD6 ET12 ET5 6.6 156 green Example 29 HT3 HT11 EM14 B-27 GD5 ET12 ET2 6.3 131 green Example 30 HT3 HT12 EM14 D-2 GD5 ET11 ET2 6.3 140 green Example 31 HT3 HT11 EM14 D-1 GD1 ET12 ET2 6.4 130 green Example 32 HT3 HT12 EM33 B-27 GD7 ET11 ET2 6.2 95 green Example 33 HT2 HT12 EM13 C-11 GD9 ET12 ET2 5.8 143 green Example 34 HT2 HT12 EM9 C-21 RD1 ET12 ET2 6.2 151 red Example 35 HT3 HT10 EM9 D-6 RD1 ET12 ET2 6.1 154 red Example 36 HT2 HT12 EM9 D-13 RD1 ET11 ET5 5.9 170 red Example 37 HT3 HT10 EM9 B-15 RD1 ET12 ET2 5.2 125 red Example 38 HT2 HT12 EM9 B-27 RD1 ET11 ET5 5.2 135 red Example 39 HT3 HT11 EM11 C-21 RD2 ET11 ET2 5.9 149 red Example 40 HT3 HT12 EM11 C-16 RD2 ET12 ET2 6.5 158 red Example 41 HT3 HT11 EM32 C-1 RD2 ET12 ET2 6.3 105 red Comparative HT3 HT11 EM14 comparative GD5 ET12 ET2 4.9 89 green example 1 compound 1 Comparative HT3 HT12 EM9 comparative RD1 ET12 ET2 3.9 135 red example 2 compound 2

Table 7 indicates that in Comparative examples 1 and 2, the maximum external quantum efficiencies (E.Q.E.) are as low as 4.9% and 3.9%. The reason for this is that the large difference between S₁ and T₁ results in a few emission components originating from delayed fluorescence. In each of the devices of Examples 24 to 41, the difference between S₁ and T₁ was small because of the electron-withdrawing carbonyl group and the electron-donating amino group substituted with the sterically hindering group X₂; thus, the devices exhibited high luminous efficiency owing to delayed fluorescence.

The 5% degradation lifetime (LT95) in Comparative example 1 was 89 hours, indicating poor durability characteristics. The reason for this is presumably that this compound has a high molecular aspect ratio and thus is prone to molecular association, crystallization, and to have poor film properties. In contrast, the 5% degradation lifetime (LT95) of each of the devices in Examples 24 to 41 was 95 hours or more, indicating good durability characteristics. In addition, the presence of the X₂-containing amino group as a substituent that reduces the degree of molecular flatness in the basic skeleton having a high degree of flatness is thought to have resulted in a low molecular aspect ratio and a film having a high degree of amorphous nature, exhibiting good durability characteristics.

The organic compound according to an embodiment of the present disclosure has a structure with superior luminescence properties and film properties. Thus, the use of the organic compound according to an embodiment of the present disclosure for an organic light-emitting device enables the organic light-emitting device to have excellent luminous efficiency and driving durability characteristics.

While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2021-051398 filed Mar. 25, 2021, which is hereby incorporated by reference herein in its entirety. 

What is claimed is:
 1. An organic compound represented by formula [1]:

where in formula [1], R₁ to R₈ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, X₁ is oxygen, sulfur, selenium, tellurium, or a CR₉R₁₀ group, where R₉ and R₁₀ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, wherein at least one of R₁ to R₈ is a group represented by formula [2]:

where in formula [2], R₁₁ to R₁₅ are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a silyl group, and a cyano group, and *1 represents a binding position, wherein at least one of R₁₁ to R₁₅ is an amino group represented by any of formulae [3-1] to [3-30], and each of the amino groups represented by formulae [3-1] to [3-30] optionally further contains a substituent,

where in formulae [3-1] to [3-30], each X₂ is independently selected from the group consisting of a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, and a substituted or unsubstituted pyridyl group, and each *2 represents a binding position.
 2. The organic compound according to claim 1, wherein at least one of groups in one of a set of R₁ to R₄ and a set of R₅ to R₈ is a group represented by formula [2].
 3. The organic compound according to claim 2, wherein groups in another set of the set of R₁ to R₄ and the set of R₅ to R₈ are each selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, and a cyano group.
 4. The organic compound according to claim 1, wherein X₁ is oxygen or sulfur.
 5. The organic compound according to claim 1, wherein at least one of the group consisting of R₁₁, R₁₂, R₁₄, and R₁₅ is an amino group represented by any of formulae [3-1] to [3-30].
 6. The organic compound according to claim 5, wherein R₁₃ is selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, and a substituted or unsubstituted phenyl group.
 7. The organic compound according to claim 1, wherein X₂ is a substituted or unsubstituted alkyl group.
 8. The organic compound according to claim 1, wherein each of the amino groups represented by formulae [3-1] to [3-30] optionally contains a substituent selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a phenyl group, a biphenyl group, a naphthyl group, a pyridyl group, a pyrazinyl group, a triazinyl group, a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, a ditolylamino group, a methoxy group, an ethoxy group, a propoxy group, a phenoxy group, fluorine, chlorine, bromine, iodine, and a cyano group.
 9. An organic light-emitting device, comprising: an anode; a cathode; and at least one organic compound layer disposed between the anode and the cathode, wherein at least one layer of the at least one organic compound layer contains the organic compound according to claim
 1. 10. The organic light-emitting device according to claim 9, wherein the at least one layer containing the organic compound is a light-emitting layer.
 11. The organic light-emitting device according to claim 10, wherein the light-emitting layer further contains a host material.
 12. The organic light-emitting device according to claim 11, wherein the host material is a hydrocarbon compound.
 13. The organic light-emitting device according to claim 11, wherein the light-emitting layer further contains a light-emitting material.
 14. The organic light-emitting device according to claim 13, wherein the light-emitting material is a hydrocarbon compound.
 15. The organic light-emitting device according to claim 10, wherein the light-emitting layer emits green light or red light.
 16. A display apparatus, comprising: multiple pixels, at least one of the multiple pixels including: the organic light-emitting device according to claim 9, and an active element coupled to the organic light-emitting device.
 17. A photoelectric conversion apparatus, comprising: an optical unit including multiple lenses; an image pickup device configured to receive light passing through the optical unit; and a display unit configured to display an image captured by the image pickup device, wherein the display unit includes the organic light-emitting device according to claim
 9. 18. An electronic apparatus, comprising: a display unit including the organic light-emitting device according to claim 9; a housing provided with the display unit; and a communication unit being disposed in the housing and communicating with an outside.
 19. A lighting apparatus, comprising: a light source including the organic light-emitting device according to claim 9; and a light diffusion unit or an optical filter configured to transmit light emitted from the light source.
 20. A moving object, comprising: a lighting unit including the organic light-emitting device according to claim 9; and a body provided with the lighting unit.
 21. An exposure light source for an electrophotographic image-forming apparatus, comprising: the organic light-emitting device according to claim
 9. 